Seeds to Sow in May
May is one of the highpoints in the gardening year: spring profusion is at its peak and everywhere plants are in full,
lush growth. Generally, the weather is changeable still, but often warmer and sunnier, and increasingly, as our climate warms,
drier. May is the month when the garden really shows its potential and thoughts easily turn to balmy summer days.
Growing conditions in May vary dramatically so keep an eye on the weather, those night time temperatures and your soil conditions
before you begin sowing. It’s certainly not too late to still sow seeds of many garden favourites; the good growing conditions mean
that seeds should germinate freely, so long as you can provide seedlings with the water they require. Some vegetables such as sweetcorn,
courgettes, marrows, tomatoes and runner beans are temperature sensitive and if sown in soil that is too cold will fail to germinate well.
Seedlings that get off to a bad start may not recover. Even in May it is still best to start these more sensitive seeds indoors or in a
greenhouse to give them the best chance.
To see all seeds that can be sown in May, take a look here.
Top Seeds to Sow in May
Nasturtium
Sow nasturtiums outside in pots, containers and in borders where they are to flower. Seeds usually take up to two weeks to sprout, although if soaked in water overnight properly before planting, they can often germinate within seven days.
Nasturtiums come in all sorts of beautiful mixes, ideal for adding a splash of bright colour to your pots.
Use them in companion planting near your peas and beans to draw aphids away. You can also eat their edible petals.
Try growing Unwins Nasturtium Whirlybird Mix. This is a blend of upward-facing flowers. The flowers have beautiful shades of red, orange and peach that stand away from the foliage.
Peas
From mangetout to earlies to sugar snap peas, there are so many different types of peas to be sown this month.
Sow your peas directly into the ground in a flat-bottomed trench 5cm deep, 7cm apart in zig-zag pattern drills (rows). This will make the best use of your space for the maximum number of peas.
For an award-winning variety, try Unwins Mangetout Snow Pea Delikata Seeds. An RHS Award of Garden Merit variety producing versatile mangetout as well as shelled peas.
You can pick deliciously sweet mangetout pods or wait until the pods are bulging and then shell out the equally sweet peas.
Broccoli
A superfood with lots of vitamins and nutrients. Broccoli is a must grow this month.
Broccoli is from the brassica family and generally crops in summer and autumn so there's plenty of time to enjoy!
Sow directly into wherever you are growing your veg; three seeds to every 30cm, and then thin this to one plant after germination. If the weather is cold, sow in modular trays for transplanting outside when it gets warmer.
Try growing Broccoli Parthenon F1, with its long cropping period, producing large domes of finely-beaded heads with an excellent flavour, this is a great choice. Enjoy this broccoli boiled or roasted, for a tasty addition to your plate.
Sunflowers
Directly sow your sunflower seeds outdoors now for flowering this year in late summer and autumn.
Sunflowers will give you a dramatic display of colour in your garden. With lots of varieties to choose from in different sizes and colours, you'll be sure to find something to make an impact.
Sunflowers will give your garden instant style as well as making a great cut flower. They are also a natural food source for wild birds, and fun to grow with children.
For a beautiful mix of colours, try sowing Unwins Sunflower Vincent's Mix. Including yellows, reds and oranges, this is a great mix for plenty of variety in your garden.
Other seeds to sow now
Flowers
Seeds to sow directly outside
- Cornflowers
- Californian poppy
- Zinnia
- Aquilegia
- Foxgloves
- Sweet Williams
Vegetables
Seeds to sow inside
- Courgette
- Cucumber
- Squash & Pumpkins
- French beans & Runner beans
- Sweetcorn
- Watercress
Vegetables
Seeds to sow directly outside
- Beetroot
- Carrots
- Radish
- Spring onions
- Swede
Herbs
Seeds to sow inside
- Rosemary
- Sage
- Thyme
Herbs
Seeds to sow directly outside
- Chives
Caring for Plants
Many seeds sown earlier in spring will be ready now for carefully pricking out from seed trays and potting on to grow as young plants. These will be delicate in the days after transplanting, so keep in a cool greenhouse or cold frame, and check on them daily. Examples include cosmos and tomatoes.
Some, but not all, young plants that have settled after potting on and have developed their third or fourth pair of true leaves many benefit now from pinching out. This may seem drastic, but it should result in really sturdy, bushy plants that flower well. Examples include petunias, marigolds, antirrhinums and cosmos.
To prepare young plants for life outdoors, begin ‘hardening off’ this month, now that the weather is warmer and the risk of frost has reduced. Stand plants outside in a sheltered, part-shaded, not too hot place during the day, or open the cold frame lid, closing or bringing in again at night. Do this for a couple of weeks before planting out.
Sweet peas can be planted out in May after hardening off, as they will then be able to resist light frost. Plant them beside netting; they may need encouragement to start climbing, so tie-in or attach with sweet pea rings. Pinch out when they reach around 10cm tall and keep well-watered.
Harvesting
It is too early to expect crops to be ready for harvest in May, but spring cabbages will be maturing nicely and chives and mint can now be cut. Early sown radishes may be ready and peas grown for their tasty shoots can also be cut. Wallflowers sown last year should be flowering this month, and if you sowed sweet peas last autumn and planted them out earlier in spring, it is possible the first flowers might appear before the end of the month.
Thinking About Next Month
June is not too late to sow seed – the last sunflowers can still be planted, as can nasturtiums, and you can direct sow nigella, limnanthes and calendula. Some perennials and biennials for flowering next year can also be sown now, such as delphiniums, lupins, foxgloves and wallflowers.